What is a degassing valve?

Pooki's Mahi's suppliers pack the coffees in a one-way degassing valve. The degassing valve allows the carbon dioxide that is released by freshly roasted coffee beans to escape without allowing flavor-robbing oxygen to get in. All Pooki's Mahi whole bean and ground (drip) coffees sold online are sealed in their airtight one-way degassing valve soon after roasting so they stay fresh until you're ready to use them.Pooki's Mahi's Single Serves are not packaged in a degassing valve.